You might want to change the port to 8080 for the MMS setting section. For the data connection setting, you don't generally need to enter DNS servers-- instead go with server assigned.

Here's the instructions for the Jamin from T-Mobile's configurator web site:

1. On the handset, tap on the Start button. 2. Tap on Settings. 3. Tap on Connections. 4. Tap on the Connections icon. 5. Under My ISP, tap on Add a new modem connection. 6. Enter T-Mo MMS in the Enter a name for the connection field. 7. Select Cellular Line (GPRS, 3G) in the drop down list of Select a modem. 8. Tap on Next. 9. Enter wap.voicestream.com in the Access point name field. Tap on Next. 10. Enter in the User name field. 11. Enter in the Password field. 12. Tap Advanced. 13. Select Use server-assigned IP address. Tap OK. 14. Tap Finish. 15. Tap OK. 16. Tap on Settings. 17. Tap on Messaging. 18. Tap on Menu which is located at the bottom right corner. 19. Tap on MMS Configuration. 20. Under Servers, tap on New. 21. Enter T-Mo MMS in the Server name field. 22. Enter 216.155.165.050 in the Gateway field. 23. Enter 8080 in the Port number field. 24. Enter http://216.155.174.84/servlets/mms in the Server Address field. 25. Select My ISP in the Connect via drop down selection. 26. Select WAP 2.0 in the WAP Version drop down selection. 27. Tap on OK. 28. Tap on Set As Default. 29. Tap OK.